diff mbox series

[RFC,1/7] riscv: kvm: add support for FWFT SBI extension

Message ID 20240418142701.1493091-2-cleger@rivosinc.com (mailing list archive)
State RFC
Headers show
Series riscv: Add support for Ssdbltrp extension | expand

Checks

Context Check Description
conchuod/vmtest-fixes-PR fail merge-conflict

Commit Message

Clément Léger April 18, 2024, 2:26 p.m. UTC 
Add support for FWFT extension in KVM

Signed-off-by: Clément Léger <cleger@rivosinc.com>
---
 arch/riscv/include/asm/kvm_host.h          |   5 +
 arch/riscv/include/asm/kvm_vcpu_sbi.h      |   1 +
 arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h |  37 ++++++
 arch/riscv/include/uapi/asm/kvm.h          |   1 +
 arch/riscv/kvm/Makefile                    |   1 +
 arch/riscv/kvm/vcpu.c                      |   5 +
 arch/riscv/kvm/vcpu_sbi.c                  |   4 +
 arch/riscv/kvm/vcpu_sbi_fwft.c             | 136 +++++++++++++++++++++
 8 files changed, 190 insertions(+)
 create mode 100644 arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
 create mode 100644 arch/riscv/kvm/vcpu_sbi_fwft.c

Comments

Deepak Gupta April 26, 2024, 11:44 p.m. UTC | #1 
On Thu, Apr 18, 2024 at 04:26:40PM +0200, Clément Léger wrote:
>Add support for FWFT extension in KVM
>
>Signed-off-by: Clément Léger <cleger@rivosinc.com>
>---
> arch/riscv/include/asm/kvm_host.h          |   5 +
> arch/riscv/include/asm/kvm_vcpu_sbi.h      |   1 +
> arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h |  37 ++++++
> arch/riscv/include/uapi/asm/kvm.h          |   1 +
> arch/riscv/kvm/Makefile                    |   1 +
> arch/riscv/kvm/vcpu.c                      |   5 +
> arch/riscv/kvm/vcpu_sbi.c                  |   4 +
> arch/riscv/kvm/vcpu_sbi_fwft.c             | 136 +++++++++++++++++++++
> 8 files changed, 190 insertions(+)
> create mode 100644 arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
> create mode 100644 arch/riscv/kvm/vcpu_sbi_fwft.c
>
>diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
>index 484d04a92fa6..be60aaa07f57 100644
>--- a/arch/riscv/include/asm/kvm_host.h
>+++ b/arch/riscv/include/asm/kvm_host.h
>@@ -19,6 +19,7 @@
> #include <asm/kvm_vcpu_fp.h>
> #include <asm/kvm_vcpu_insn.h>
> #include <asm/kvm_vcpu_sbi.h>
>+#include <asm/kvm_vcpu_sbi_fwft.h>
> #include <asm/kvm_vcpu_timer.h>
> #include <asm/kvm_vcpu_pmu.h>
>
>@@ -169,6 +170,7 @@ struct kvm_vcpu_csr {
> struct kvm_vcpu_config {
> 	u64 henvcfg;
> 	u64 hstateen0;
>+	u64 hedeleg;
> };
>
> struct kvm_vcpu_smstateen_csr {
>@@ -261,6 +263,9 @@ struct kvm_vcpu_arch {
> 	/* Performance monitoring context */
> 	struct kvm_pmu pmu_context;
>
>+	/* Firmware feature SBI extension context */
>+	struct kvm_sbi_fwft fwft_context;
>+
> 	/* 'static' configurations which are set only once */
> 	struct kvm_vcpu_config cfg;
>
>diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
>index b96705258cf9..3a33bbacc233 100644
>--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
>+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
>@@ -86,6 +86,7 @@ extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst;
> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn;
> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta;
>+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_fwft;
> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
>
>diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
>new file mode 100644
>index 000000000000..7dc1b80c7e6c
>--- /dev/null
>+++ b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
>@@ -0,0 +1,37 @@
>+/* SPDX-License-Identifier: GPL-2.0-only */
>+/*
>+ * Copyright (c) 2023 Rivos Inc
>+ *
>+ * Authors:
>+ *     Atish Patra <atishp@rivosinc.com>

nit: probably need to fix Copyright year and Authors here :-)
Same in all new files being introduced.

>+ */
>+
>+#ifndef __KVM_VCPU_RISCV_FWFT_H
>+#define __KVM_VCPU_RISCV_FWFT_H
>+
>+#include <asm/sbi.h>
>+
>+#define KVM_SBI_FWFT_FEATURE_COUNT	1
>+
>+static int kvm_sbi_fwft_set(struct kvm_vcpu *vcpu,
>+			    enum sbi_fwft_feature_t feature,
>+			    unsigned long value, unsigned long flags)
>+{
>+	struct kvm_sbi_fwft_config *conf = kvm_sbi_fwft_get_config(vcpu,
>+								   feature);
>+	if (!conf)
>+		return SBI_ERR_DENIED;

Curious,
Why denied and not something like NOT_SUPPORTED NOT_AVAILABLE here?

>+
>+	if ((flags & ~SBI_FWFT_SET_FLAG_LOCK) != 0)
>+		return SBI_ERR_INVALID_PARAM;
>+
>+	if (conf->flags & SBI_FWFT_SET_FLAG_LOCK)
>+		return SBI_ERR_DENIED;
>+
>+	conf->flags = flags;
>+
>+	return conf->feature->set(vcpu, conf, value);
>+}
>+
Clément Léger April 30, 2024, 7:26 a.m. UTC | #2 
On 27/04/2024 01:44, Deepak Gupta wrote:
> On Thu, Apr 18, 2024 at 04:26:40PM +0200, Clément Léger wrote:
>> Add support for FWFT extension in KVM
>>
>> Signed-off-by: Clément Léger <cleger@rivosinc.com>
>> ---
>> arch/riscv/include/asm/kvm_host.h          |   5 +
>> arch/riscv/include/asm/kvm_vcpu_sbi.h      |   1 +
>> arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h |  37 ++++++
>> arch/riscv/include/uapi/asm/kvm.h          |   1 +
>> arch/riscv/kvm/Makefile                    |   1 +
>> arch/riscv/kvm/vcpu.c                      |   5 +
>> arch/riscv/kvm/vcpu_sbi.c                  |   4 +
>> arch/riscv/kvm/vcpu_sbi_fwft.c             | 136 +++++++++++++++++++++
>> 8 files changed, 190 insertions(+)
>> create mode 100644 arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
>> create mode 100644 arch/riscv/kvm/vcpu_sbi_fwft.c
>>
>> diff --git a/arch/riscv/include/asm/kvm_host.h
>> b/arch/riscv/include/asm/kvm_host.h
>> index 484d04a92fa6..be60aaa07f57 100644
>> --- a/arch/riscv/include/asm/kvm_host.h
>> +++ b/arch/riscv/include/asm/kvm_host.h
>> @@ -19,6 +19,7 @@
>> #include <asm/kvm_vcpu_fp.h>
>> #include <asm/kvm_vcpu_insn.h>
>> #include <asm/kvm_vcpu_sbi.h>
>> +#include <asm/kvm_vcpu_sbi_fwft.h>
>> #include <asm/kvm_vcpu_timer.h>
>> #include <asm/kvm_vcpu_pmu.h>
>>
>> @@ -169,6 +170,7 @@ struct kvm_vcpu_csr {
>> struct kvm_vcpu_config {
>>     u64 henvcfg;
>>     u64 hstateen0;
>> +    u64 hedeleg;
>> };
>>
>> struct kvm_vcpu_smstateen_csr {
>> @@ -261,6 +263,9 @@ struct kvm_vcpu_arch {
>>     /* Performance monitoring context */
>>     struct kvm_pmu pmu_context;
>>
>> +    /* Firmware feature SBI extension context */
>> +    struct kvm_sbi_fwft fwft_context;
>> +
>>     /* 'static' configurations which are set only once */
>>     struct kvm_vcpu_config cfg;
>>
>> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h
>> b/arch/riscv/include/asm/kvm_vcpu_sbi.h
>> index b96705258cf9..3a33bbacc233 100644
>> --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
>> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
>> @@ -86,6 +86,7 @@ extern const struct kvm_vcpu_sbi_extension
>> vcpu_sbi_ext_srst;
>> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
>> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn;
>> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta;
>> +extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_fwft;
>> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
>> extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
>>
>> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
>> b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
>> new file mode 100644
>> index 000000000000..7dc1b80c7e6c
>> --- /dev/null
>> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
>> @@ -0,0 +1,37 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (c) 2023 Rivos Inc
>> + *
>> + * Authors:
>> + *     Atish Patra <atishp@rivosinc.com>
> 
> nit: probably need to fix Copyright year and Authors here :-)
> Same in all new files being introduced.
> 
>> + */
>> +
>> +#ifndef __KVM_VCPU_RISCV_FWFT_H
>> +#define __KVM_VCPU_RISCV_FWFT_H
>> +
>> +#include <asm/sbi.h>
>> +
>> +#define KVM_SBI_FWFT_FEATURE_COUNT    1
>> +
>> +static int kvm_sbi_fwft_set(struct kvm_vcpu *vcpu,
>> +                enum sbi_fwft_feature_t feature,
>> +                unsigned long value, unsigned long flags)
>> +{
>> +    struct kvm_sbi_fwft_config *conf = kvm_sbi_fwft_get_config(vcpu,
>> +                                   feature);
>> +    if (!conf)
>> +        return SBI_ERR_DENIED;
> 
> Curious,
> Why denied and not something like NOT_SUPPORTED NOT_AVAILABLE here?

Hey Deepak,

So indeed, the return value is not totally correct since the spec states
that we return  EDENIED if feature is reserved or is platform-specific
and unimplemented. But in that case it dos not distinguish between
defined features and reserved one. I'll add a check for that.

Thanks,

Clément

> 
>> +
>> +    if ((flags & ~SBI_FWFT_SET_FLAG_LOCK) != 0)
>> +        return SBI_ERR_INVALID_PARAM;
>> +
>> +    if (conf->flags & SBI_FWFT_SET_FLAG_LOCK)
>> +        return SBI_ERR_DENIED;
>> +
>> +    conf->flags = flags;
>> +
>> +    return conf->feature->set(vcpu, conf, value);
>> +}
>> +
diff mbox series

Patch

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 484d04a92fa6..be60aaa07f57 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -19,6 +19,7 @@ 
 #include <asm/kvm_vcpu_fp.h>
 #include <asm/kvm_vcpu_insn.h>
 #include <asm/kvm_vcpu_sbi.h>
+#include <asm/kvm_vcpu_sbi_fwft.h>
 #include <asm/kvm_vcpu_timer.h>
 #include <asm/kvm_vcpu_pmu.h>
 
@@ -169,6 +170,7 @@  struct kvm_vcpu_csr {
 struct kvm_vcpu_config {
 	u64 henvcfg;
 	u64 hstateen0;
+	u64 hedeleg;
 };
 
 struct kvm_vcpu_smstateen_csr {
@@ -261,6 +263,9 @@  struct kvm_vcpu_arch {
 	/* Performance monitoring context */
 	struct kvm_pmu pmu_context;
 
+	/* Firmware feature SBI extension context */
+	struct kvm_sbi_fwft fwft_context;
+
 	/* 'static' configurations which are set only once */
 	struct kvm_vcpu_config cfg;
 
diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index b96705258cf9..3a33bbacc233 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -86,6 +86,7 @@  extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_fwft;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
 
diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
new file mode 100644
index 000000000000..7dc1b80c7e6c
--- /dev/null
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h
@@ -0,0 +1,37 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2023 Rivos Inc
+ *
+ * Authors:
+ *     Atish Patra <atishp@rivosinc.com>
+ */
+
+#ifndef __KVM_VCPU_RISCV_FWFT_H
+#define __KVM_VCPU_RISCV_FWFT_H
+
+#include <asm/sbi.h>
+
+#define KVM_SBI_FWFT_FEATURE_COUNT	1
+
+struct kvm_sbi_fwft_config;
+struct kvm_vcpu;
+
+struct kvm_sbi_fwft_feature {
+	enum sbi_fwft_feature_t id;
+	int (*set)(struct kvm_vcpu *vcpu, struct kvm_sbi_fwft_config *conf, unsigned long value);
+	int (*get)(struct kvm_vcpu *vcpu, struct kvm_sbi_fwft_config *conf, unsigned long *value);
+};
+
+struct kvm_sbi_fwft_config {
+	const struct kvm_sbi_fwft_feature *feature;
+	unsigned long flags;
+};
+
+/* FWFT data structure per vcpu */
+struct kvm_sbi_fwft {
+	struct kvm_sbi_fwft_config configs[KVM_SBI_FWFT_FEATURE_COUNT];
+};
+
+#define vcpu_to_fwft(vcpu) (&(vcpu)->arch.fwft_context)
+
+#endif /* !__KVM_VCPU_RISCV_FWFT_H */
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 7499e88a947c..fa3097da91c0 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -185,6 +185,7 @@  enum KVM_RISCV_SBI_EXT_ID {
 	KVM_RISCV_SBI_EXT_VENDOR,
 	KVM_RISCV_SBI_EXT_DBCN,
 	KVM_RISCV_SBI_EXT_STA,
+	KVM_RISCV_SBI_EXT_FWFT,
 	KVM_RISCV_SBI_EXT_MAX,
 };
 
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index c9646521f113..19175bd5b40a 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -27,6 +27,7 @@  kvm-y += vcpu_sbi_base.o
 kvm-y += vcpu_sbi_replace.o
 kvm-y += vcpu_sbi_hsm.o
 kvm-y += vcpu_sbi_sta.o
+kvm-y += vcpu_sbi_fwft.o
 kvm-y += vcpu_timer.o
 kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o vcpu_sbi_pmu.o
 kvm-y += aia.o
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index b5ca9f2e98ac..461ef60d4eda 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -505,6 +505,8 @@  static void kvm_riscv_vcpu_setup_config(struct kvm_vcpu *vcpu)
 		if (riscv_isa_extension_available(isa, SMSTATEEN))
 			cfg->hstateen0 |= SMSTATEEN0_SSTATEEN0;
 	}
+
+	cfg->hedeleg = csr_read(CSR_HEDELEG);
 }
 
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
@@ -521,6 +523,7 @@  void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	csr_write(CSR_VSTVAL, csr->vstval);
 	csr_write(CSR_HVIP, csr->hvip);
 	csr_write(CSR_VSATP, csr->vsatp);
+	csr_write(CSR_HEDELEG, cfg->hedeleg);
 	csr_write(CSR_HENVCFG, cfg->henvcfg);
 	if (IS_ENABLED(CONFIG_32BIT))
 		csr_write(CSR_HENVCFGH, cfg->henvcfg >> 32);
@@ -551,6 +554,7 @@  void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
 	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;
 
 	vcpu->cpu = -1;
 
@@ -574,6 +578,7 @@  void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 	csr->vstval = csr_read(CSR_VSTVAL);
 	csr->hvip = csr_read(CSR_HVIP);
 	csr->vsatp = csr_read(CSR_VSATP);
+	cfg->hedeleg = csr_read(CSR_HEDELEG);
 }
 
 static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index 72a2ffb8dcd1..76901f0f34b7 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -74,6 +74,10 @@  static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
 		.ext_idx = KVM_RISCV_SBI_EXT_STA,
 		.ext_ptr = &vcpu_sbi_ext_sta,
 	},
+	{
+		.ext_idx = KVM_RISCV_SBI_EXT_FWFT,
+		.ext_ptr = &vcpu_sbi_ext_fwft,
+	},
 	{
 		.ext_idx = KVM_RISCV_SBI_EXT_EXPERIMENTAL,
 		.ext_ptr = &vcpu_sbi_ext_experimental,
diff --git a/arch/riscv/kvm/vcpu_sbi_fwft.c b/arch/riscv/kvm/vcpu_sbi_fwft.c
new file mode 100644
index 000000000000..b9b7f8fa6d22
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_sbi_fwft.c
@@ -0,0 +1,136 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Atish Patra <atish.patra@wdc.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+#include <asm/sbi.h>
+#include <asm/kvm_vcpu_sbi.h>
+#include <asm/kvm_vcpu_sbi_fwft.h>
+
+#define MIS_DELEG (1UL << EXC_LOAD_MISALIGNED | 1UL << EXC_STORE_MISALIGNED)
+
+static int kvm_sbi_fwft_set_misaligned_delegation(struct kvm_vcpu *vcpu,
+					struct kvm_sbi_fwft_config *conf,
+					unsigned long value)
+{
+	if (value)
+		csr_set(CSR_HEDELEG, MIS_DELEG);
+	else
+		csr_clear(CSR_HEDELEG, MIS_DELEG);
+
+	return SBI_SUCCESS;
+}
+
+static int kvm_sbi_fwft_get_misaligned_delegation(struct kvm_vcpu *vcpu,
+					struct kvm_sbi_fwft_config *conf,
+					unsigned long *value)
+{
+	*value = (csr_read(CSR_HEDELEG) & MIS_DELEG) != 0;
+
+	return SBI_SUCCESS;
+}
+
+static struct kvm_sbi_fwft_config *
+kvm_sbi_fwft_get_config(struct kvm_vcpu *vcpu, enum sbi_fwft_feature_t feature)
+{
+	int i = 0;
+	struct kvm_sbi_fwft *fwft = vcpu_to_fwft(vcpu);
+
+	for (i = 0; i < KVM_SBI_FWFT_FEATURE_COUNT; i++) {
+		if (fwft->configs[i].feature->id == feature)
+			return &fwft->configs[i];
+	}
+
+	return NULL;
+}
+
+static int kvm_sbi_fwft_set(struct kvm_vcpu *vcpu,
+			    enum sbi_fwft_feature_t feature,
+			    unsigned long value, unsigned long flags)
+{
+	struct kvm_sbi_fwft_config *conf = kvm_sbi_fwft_get_config(vcpu,
+								   feature);
+	if (!conf)
+		return SBI_ERR_DENIED;
+
+	if ((flags & ~SBI_FWFT_SET_FLAG_LOCK) != 0)
+		return SBI_ERR_INVALID_PARAM;
+
+	if (conf->flags & SBI_FWFT_SET_FLAG_LOCK)
+		return SBI_ERR_DENIED;
+
+	conf->flags = flags;
+
+	return conf->feature->set(vcpu, conf, value);
+}
+
+static int kvm_sbi_fwft_get(struct kvm_vcpu *vcpu,
+			    enum sbi_fwft_feature_t feature,
+			    unsigned long *value)
+{
+	struct kvm_sbi_fwft_config *conf = kvm_sbi_fwft_get_config(vcpu,
+								   feature);
+	if (!conf)
+		return SBI_ERR_DENIED;
+
+	return conf->feature->get(vcpu, conf, value);
+}
+
+static int kvm_sbi_ext_fwft_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
+				    struct kvm_vcpu_sbi_return *retdata)
+{
+	int ret = 0;
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	unsigned long funcid = cp->a6;
+
+	switch (funcid) {
+	case SBI_EXT_FWFT_SET:
+		ret = kvm_sbi_fwft_set(vcpu, cp->a0, cp->a1, cp->a2);
+		break;
+	case SBI_EXT_FWFT_GET:
+		ret = kvm_sbi_fwft_get(vcpu, cp->a0, &retdata->out_val);
+		break;
+	default:
+		ret = SBI_ERR_NOT_SUPPORTED;
+		break;
+	}
+
+	retdata->err_val = ret;
+
+	return 0;
+}
+
+static const struct kvm_sbi_fwft_feature features[] = {
+	{
+		.id = SBI_FWFT_MISALIGNED_DELEG,
+		.set = kvm_sbi_fwft_set_misaligned_delegation,
+		.get = kvm_sbi_fwft_get_misaligned_delegation,
+	}
+};
+
+static_assert(ARRAY_SIZE(features) == KVM_SBI_FWFT_FEATURE_COUNT);
+
+
+static unsigned long kvm_sbi_ext_fwft_probe(struct kvm_vcpu *vcpu)
+{
+	struct kvm_sbi_fwft *fwft = vcpu_to_fwft(vcpu);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(features); i++)
+		fwft->configs[i].feature = &features[i];
+
+	return 1;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_fwft = {
+	.extid_start = SBI_EXT_FWFT,
+	.extid_end = SBI_EXT_FWFT,
+	.handler = kvm_sbi_ext_fwft_handler,
+	.probe = kvm_sbi_ext_fwft_probe,
+};